I have a 3 handle shower with the ugly acrylic knobs. When one broke, I went to Home Depot to replace and found that due to the square adapter on the end of each valve, I could only replace with newer ugly acrylic handles. So, I got them replaced. It was no easy task. Stripped screw, screw extractor broke in the stripped screw, etc... Now, they're leaking from the handle. I have no idea what to do other than replace the valve and I have no idea what type of valve etc. Is there anything else I can do? All the plumbing is behind the wall and we're selling our house, so I really don't want to destroy anything. I just want to make sure it doesn't leak. Any help would be appreciated.

On a related note, while taking a shower in the other bathroom, I turned the shower inverter and it literally broke off in my hand. Just my luck...

A picture, model or brand would help us. If you just replaced the plastic handles the valve should not leak. I think you may have lossen the stem or cartridge trying to get the old handles off. Remove the new handles and see if there is a nut shapped ring under the handle that can be tightened. Most mixing valves can be completely rebuilt without tearing out any walls.